Hydrographic buoy



FIG. 1 is a front perspective view of a hydrographic buoy showing the new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a lefthand side elevational view thereof;

FIG. 6 is a rear elevational view thereof; and,

FIG. 7 is a righthand side elevational view thereof. 

The ornamental design for hydrographic buoy, as shown. 